Quantum Sensing of Copper-Phthalocyanine Electron Spins via NV Relaxometry

• URL: http://arxiv.org/abs/2511.03200v1
• Date: Wed, 05 Nov 2025 05:33:13 GMT
• Title: Quantum Sensing of Copper-Phthalocyanine Electron Spins via NV Relaxometry
• Authors: Boning Li, Xufan Li, Yifan Quan, Avetik R Harutyunyan, Paola Cappellaro,
• Abstract summary: Molecular spin systems are promising candidates for quantum information processing and nanoscale sensing.<n>We use $T_1$ relaxometry of shallow nitrogen-vacancy centers in diamond to probe the electron spin ensemble of a polycrystalline copper phthalocyanine thin film.<n>Our results establish NV centers as powerful probes for molecular spin systems, providing insights into molecular qubits, spin bath engineering, and hybrid quantum materials.
• Score: 5.279375755987053
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Molecular spin systems are promising candidates for quantum information processing and nanoscale sensing, yet their characterization at room temperature remains challenging due to fast spin decoherence. In this work, we use $T_1$ relaxometry of shallow nitrogen-vacancy (NV) centers in diamond to probe the electron spin ensemble of a polycrystalline copper phthalocyanine (CuPc) thin film. In addition to unequivocally identifying the NV-CuPc interaction thanks to its hyperfine spectrum, we further extract key parameters of the CuPc spin ensemble, including its correlation time and local lattice orientation, that cannot be measured in bulk electron resonance experiments. The analysis of our experimental results confirms that electron-electron interactions dominate the decoherence dynamics of CuPc at room temperature. Additionally, we demonstrate that the CuPc-enhanced NV relaxometry can serve as a robust method to estimate the NV depth with $\sim1$~nm precision. Our results establish NV centers as powerful probes for molecular spin systems, providing insights into molecular qubits, spin bath engineering, and hybrid quantum materials, and offering a potential pathway toward their applications such as molecular-scale quantum processors and spin-based quantum networks.

Related papers

• Exploring the mechanisms of transverse relaxation of copper(II)-phthalocyanine spin qubits [9.695800379962364]
  Molecular spin qubits are promising candidates for quantum technologies, but their performance is limited by decoherence arising from diverse mechanisms.<n>Here we present a systematic experimental and theoretical framework for analyzing the mechanisms of transverse relaxation in copper(II) phthalocyanine (CuPc) diluted into diamagnetic phthalocyanine hosts.<n>Our work identifies favorable values of the electron spin density for quantum applications, and provides a transferable methodology for predicting ensemble coherence times.
  arXiv  Detail & Related papers  (2025-11-05T05:32:56Z)
• Spin-Electric Control of Individual Molecules on Surfaces [0.0]
  We present spin-electric coupling (SEC) for two molecular spin systems, iron phthalocyanine (FePc) and Fe-FePc complexes, adsorbed on a surface.<n>We show that the spin dynamics can be tuned, demonstrating a pathway towards electrically controlled quantum operation.
  arXiv  Detail & Related papers  (2025-07-18T07:03:05Z)
• An electrically controlled single molecule spin switch [0.0]
  We present an electrically controlled single-molecule spin switch based on a bistable complex adsorbed on an insulating magnesium oxide film.<n>Inelastic electron tunnelling spectroscopy (IETS) measurements and density functional theory (DFT) calculations reveal a distinct change between a paramagnetic and a non-magnetic spin configuration.
  arXiv  Detail & Related papers  (2025-03-26T14:42:25Z)
• Spin decoherence in VOPc@graphene nanoribbon complexes [5.691318972818067]
  Carbon nanoribbon or nanographene qubit arrays can facilitate quantum-to-quantum transduction between light, charge, and spin. We study spin decoherence due to coupling with a surrounding nuclear spin bath of an electronic molecular spin of a vanadyl phthalocyanine (VOPc) molecule integrated on an armchair-edged graphene nanoribbon (GNR) We find that the decoherence time $T$ is anisotropic with respect to magnetic field orientation and determined only by nuclear spins on VOPc and GNR.
  arXiv  Detail & Related papers  (2023-07-31T04:55:05Z)
• Control of an environmental spin defect beyond the coherence limit of a central spin [79.16635054977068]
  We present a scalable approach to increase the size of electronic-spin registers. We experimentally realize this approach to demonstrate the detection and coherent control of an unknown electronic spin outside the coherence limit of a central NV. Our work paves the way for engineering larger quantum spin registers with the potential to advance nanoscale sensing, enable correlated noise spectroscopy for error correction, and facilitate the realization of spin-chain quantum wires for quantum communication.
  arXiv  Detail & Related papers  (2023-06-29T17:55:16Z)
• Relativistic aspects of orbital and magnetic anisotropies in the chemical bonding and structure of lanthanide molecules [60.17174832243075]
  We study the electronic and ro-vibrational states of heavy homonuclear lanthanide Er2 and Tm2 molecules by applying state-of-the-art relativistic methods. We were able to obtain reliable spin-orbit and correlation-induced splittings between the 91 Er2 and 36 Tm2 electronic potentials dissociating to two ground-state atoms.
  arXiv  Detail & Related papers  (2021-07-06T15:34:00Z)
• Demonstration of electron-nuclear decoupling at a spin clock transition [54.088309058031705]
  Clock transitions protect molecular spin qubits from magnetic noise. linear coupling to nuclear degrees of freedom causes a modulation and decay of electronic coherence. An absence of quantum information leakage to the nuclear bath provides opportunities to characterize other decoherence sources.
  arXiv  Detail & Related papers  (2021-06-09T16:23:47Z)
• Anisotropic electron-nuclear interactions in a rotating quantum spin bath [55.41644538483948]
  Spin-bath interactions are strongly anisotropic, and rapid physical rotation has long been used in solid-state nuclear magnetic resonance. We show that the interaction between electron spins of nitrogen-vacancy centers and a bath of $13$C nuclear spins introduces decoherence into the system. Our findings offer new insights into the use of physical rotation for quantum control with implications for quantum systems having motional and rotational degrees of freedom that are not fixed.
  arXiv  Detail & Related papers  (2021-05-16T06:15:00Z)
• Controlled coherent dynamics of [VO(TPP)], a prototype molecular nuclear qudit with an electronic ancilla [50.002949299918136]
  We show that [VO(TPP)] (vanadyl tetraphenylporphyrinate) is a promising system suitable to implement quantum computation algorithms. It embeds an electronic spin 1/2 coupled through hyperfine interaction to a nuclear spin 7/2, both characterized by remarkable coherence.
  arXiv  Detail & Related papers  (2021-03-15T21:38:41Z)
• Chemical tuning of spin clock transitions in molecular monomers based on nuclear spin-free Ni(II) [52.259804540075514]
  We report the existence of a sizeable quantum tunnelling splitting between the two lowest electronic spin levels of mononuclear Ni complexes. The level anti-crossing, or magnetic clock transition, associated with this gap has been directly monitored by heat capacity experiments. The comparison of these results with those obtained for a Co derivative, for which tunnelling is forbidden by symmetry, shows that the clock transition leads to an effective suppression of intermolecular spin-spin interactions.
  arXiv  Detail & Related papers  (2021-03-04T13:31:40Z)
• Ab initio Ultrafast Spin Dynamics in Solids [0.7874708385247353]
  We present a first-principles real-time density-matrix approach based on Lindblad dynamics to simulate ultrafast spin dynamics for general solid-state systems. We find that the electron-electron scattering is negligible at room temperature but becomes dominant at low temperatures for spin relaxation in n-type GaAs.
  arXiv  Detail & Related papers  (2020-12-16T02:49:47Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.